<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
</head>
<body>
<div id="app">
    <p>{{msg|foo}}</p>
    <p>{{msg|foo('dap')}}</p>
</div>
<script src="vue.js"></script>
<script>
    Vue.filter('foo', function (input, format) {
        format = format || 'liu';
        return input.replace(/天/g, format)
    });
    var vm = new Vue({
        el: '#app',
        data: {
            msg: '下雨天留客天留我不留'
        }

    })
</script>
</body>
</html>